The present invention relates generally to weight lifting exercise machines, and is particularly concerned with a leg exercise apparatus for such machines.
Weight lifting machines normally have a leg extension/leg curl arm pivoted at the front end of the machine adjacent the seat and linked to the exercise resistance to permit a user to perform leg exercises. Such devices are described, for example, in U.S. Pat. Nos. 4,678,185 and 4,915,377 of Mahnke. The exercise arm in these machines is straight. In some prior art leg exercise arms, a pulley is mounted on the straight arm, for example the 880-3D Howe Gym of Hoist Fitness Systems has a pulley at the end of the straight exercise arm. The problem with straight leg exercise arms is that the exerciser will experience a drop off or reduction in resistance while performing an exercise. This is because the exercise arm goes through an arcing motion, and the cable attached to the arm is therefore not pulled at a constant rate. The first half of the movement pulls more cable than the second half, causing a drop off in resistance. In order to prevent the drop off in resistance, some manufacturers have attached a cam or curved piece of metal to the end of the exercise arm, providing a surface for the cable to wrap around during the second half of an exercise movement, so that the cable is pulled at an even rate during the entire movement. However, this adds to the expense of the machine and also causes design restrictions due to the rearward protrusion of the cam.
Another disadvantage to the straight exercise arm is that it usually requires a stop mechanism to prevent movement in a rearward direction when tension is applied to the cabling via another exercise station.
The straight leg exercise arm also has a third disadvantage when a pulley is mounted at the end of the arm for performing other exercises such as upper body, standing position exercises. The user stands facing the machine and pulls the cable upward using various handle attachments. In order to perform such exercises, the exerciser must stand back from the machine to avoid damaging the cable by rubbing it against the front of the machine. This requires additional floor space. It can also be difficult to access the cable attachment point if the pulley is located at the end of the straight arm.
A further disadvantage to the straight exercise arm is its inability to provide a grip area and act as a handle for moving the exercise machine. With floor space becoming more and more of an issue in homes and health clubs, the ability to add wheels and easily maneuver equipment around is of increasing importance. It is common place for manufacturers to install wheels on their exercise equipment. These wheels are usually placed on the rear of the equipment with some sort of handle or gripping area on the opposite end. The user then bends down, grabs the handle, lifting the front end and tilting the equipment back on its wheels, where it is ready for moving. The larger/heavier the piece, the harder it is to lift and the higher the handle needs to be placed to avoid causing back strain to the lifter. Because this is difficult to achieve, most pieces with leg extension arms (particularly multi-function home gyms) do not have wheels for moving.
U.S. Pat. No. 5,393,295 of Ish describes a leg extension arm which projects forwards from the frame and has a separate rearwardly protruding cam which must be welded to the arm, making the construction relatively expensive. The arm hangs in a substantially vertical orientation. The machine is not equipped with wheels and is too large for moving safely. The leg engaging rollers are pivotally connected to the arm to accommodate various leg lengths and do not maintain a constant relationship to the cable attachment point. This will cause slight variations in resistance based on the leg roller position.
Some known exercise machines, such as the Muscle 3 machine of Tuff Stuff, have exercise arms which are straight along part of their length but which have a rearward curve in their lower portions. These generally rest in a substantially vertical orientation, and have sharp end edges around which the cable must bend at the finish of a standing leg curl exercise, which could damage the cable.
U.S. Pat. No. 5,961,428 of Webber shows an exercise machine with a forwardly curved exercise arm which has a slight bend in its lower portion, but which rests in a substantially vertical orientation and does not provide any comfortable or safe gripping area for lifting or moving the machine. The machine is not equipped with wheels for moving. A pulley mounted at the second end of the arm allows the cable end to be used in performing additional exercises.
It is an object of the present invention to provide a new and improved leg exercise arm apparatus for an exercise machine.
According to the present invention, an apparatus for performing exercises is provided, which comprises a support frame, a seat mounted on the support frame and having a forward end, an exercise arm having a first end pivoted to the support frame adjacent the forward end of the seat, and a second end, the arm having a continuous curve extending along at least a major portion of its length and bending through an arc of at least 180 degrees, the arm having a rest position in which the arm first projects forwards from the pivot and then bends back rearwards, a cable linking the arm to an exercise resistance, and a leg engaging assembly attached to the arm for engagement by the legs of a user in performing exercises.
The continuous, 180 degree rearward curve of the arm acts as a cam and provides a surface for the cable to wrap around during the exercise movement. This keeps a constant pull on the cable and helps prevent resistance drop off. In an exemplary embodiment, the second end of the arm rests against an undersurface of the seat support frame when the arm is in a rest position and acts as a stop against rearward movement of the arm when in the rest position.
The second end of the arm may be of rounded, non-sharp shape to provide a smooth, curved surface for the cable to wrap around when performing certain exercises. In one exemplary embodiment, a tubular member is mounted at the second end of the arm in an orientation transverse to the arm axis, and acts as the rearward stop. The tubular member also provides the round surface for the cable to wrap around, instead of a sharp edge at the end of an arm. The round surface at the end of the arm helps to prevent resistance drop off at the very end of an exercise movement, and prolongs cable life. This is because the cable is not bent over a sharp edge on the end of an exercise arm, as was common in prior art exercise arms. Constant bending over a sharp edge will cause the inner wire strands of a cable to fatigue and eventually break, causing premature failure of the cable.
This invention does not require a separate cam to be welded onto the exercise arm, but instead integrates the cam into the shape of the exercise arm itself. This makes the exercise arm easier and cheaper to manufacture, since it avoids the elaborate secondary welding typically required in past designs.
The upper end of the arm projects forwards before curving rearwards, providing a comfortable, easy to reach gripping area which is free of pinch points. The forward angle of the arm places the user""s wrist in a comfortable and natural position for lifting. Thus, the arm can be used as a handle for lifting or tilting the machine for moving. The gripping area is adjacent the pivot point of the exercise arm on the frame. This makes the arm less likely just to pivot when gripped and pulled upwardly, and more readily usable as a handle in lifting the machine. In an exemplary embodiment, wheels are provided at the rear end of the frame for engaging the floor when the forward end is tilted upwardly, allowing the machine to be re-positioned readily. A locking or pinning device may be provided for releasably securing the arm in position during use of the arm as a handle for lifting the forward end of the machine when moving the machine.
The leg engaging device in an exemplary embodiment comprises a pair of oppositely directed, leg engaging rollers which are positioned at the lowest point of the curved arm portion, adjacent and below the cable attachment point. This means that the resistance to the arm as felt by the user is more or less a true 100% of the amount selected. The further the cable contact point is from the leg engaging rollers, the greater the deviation in resistance felt by the user from the selected weight. With this invention, because the entire arm acts as a cam, the leg engaging rollers can be placed adjacent the cable contact or attachment point.
The leg exercise arm initially projects forwardly, yet still utilizes the second end as a stop against rearward movement. This spaces the stop away from the pivot point, eliminating rearward flex which may occur when the stop is close to the pivot. The closer a stop is to the pivot point of the arm, the greater the force it will receive when the cable is tensioned by performing an additional exercise. This arrangement avoids or reduces this problem.
The continuous, 180 degree curve of the exercise arm provides many advantages. It provides a built-in cam to keep a constant resistance throughout the exercise motion, combined with a part of the arm still projecting forward of the exercise frame pivot. The arrangement also permits the second end of the arm to act as a stop against rearward motion. The leg engaging rollers can be positioned on the curve of the arm, adjacent the lowest point of the arm and the cable contact point, to provide true, 100% exercise resistance based on the selected weight.